Sep 10, 2004 1

Motivation, Genesis & Evolutionof the eXtreme Scale Mote (XSM)

Prabal Dutta <prabal@eecs>

Sep 10, 2004 2

Acknowledgements

• Crossbow Technology– Mike Grimmer

• Ohio State– Emre Ertin

– Hui Cao

• U.C. Berkeley– Joe Polastre

– Cory Sharp

– Rob Szewczyk

• Virginia– Lin Gu

• MITRE– Ken Parker

• DARPA

Sep 10, 2004 3

Motivation: Data Collection vs. Event Detection

Data Collection

Signal Reconstruction

Reconstruction Fidelity

Data-centric

Data-driven Messaging

Periodic Sampling

High-latency Acceptable

Periodic Traffic

Store & Forward Messaging

Aggregation

Phenomena Omnichronic

Absolute Global Time

Event Detection

Signal Detection

Detection and False Alarm Rates

Meta-data Centric (e.g. statistics)

Decision-driven Messaging

Continuous “Passive Vigilance”

Low-latency Required

Bursty Traffic

Real-time Messaging

Fusion, Classification

Rare, Random, Short-lived

Relative Local Time

vs.

Sep 10, 2004 4

Differing Energy Usage Patterns

Sep 10, 2004 5

Extreme Scale Requirements

• Biggie-size “A Line in the Sand” (like PEG) Network Scale by 100x (10,000 nodes) Detection range by 6x (10m) Lifetime 8x (720hrs 1000hrs) *

• Other areas also affected, but not covered– Topology– Classification– Tracking– Routing– Time Synchronization– Localization– Application– Visualization

Sep 10, 2004 6

LITeS Concept of Operations

RadarTarget

Detected

Magnetic Target

Detected

Sep 10, 2004 7

Requirements (of the hardware platform)

• Functional– Detection, Classification (and Tracking) of:

Civilians, Soldiers and Vehicles

• Reliability– Recoverable: Even from a Byzantine program image

• Performance– Intrusion Rate: 10 intrusions per day– Lifetime: 1000 hrs of continuous operation (> 30 days)– Latency: 10 – 30 seconds– Coverage: 10km^2 (could not meet given constraints)

• Supportability– Adaptive: Dynamic reconfiguration of thresholds, etc.

Sep 10, 2004 8

Genesis: The Case for a New Platform

• Cost– Eliminate expensive parts from BOM– Eliminate unnecessary parts from BOM– Optimize for large quantity manufacturing and use

Network Scale by 100x (10,000 nodes)– Reliability: How to deal with 10K nodes with bad image

Detection range by 6x (10m)– New sensors to satisfy range/density/cost tradeoff

Lifetime 8x (720hrs 1000hrs)– Magnetometer: Tstartup = 40ms, Pss = 18mW– UWB Radar: Tstartup = 30s, Pss = 45mW– Optimistic lifetime: 6000mWh / 63mW < 100 hrs– Must lower power

• Radio– Fix anisotropic radiation and impedance mismatch

Sep 10, 2004 9

Hardware Evolution

Telos =Low-power CPU +802.15.4 Radio +Easy to useSleep-Wakeup-Active

MICAzMICA2 - CC1000 +802.15.4 RadioSleep-Wakeup-Active

XSMMICA2 + Improved RF +Low-power sensing + RecoverabilityPassive Vigilance-Wakeup-Active

XSM2XSM + Improvements +Bug Fixes

Sep 10, 2004 10

The eXtreme Scale Mote

• Key Differences between XSM and MICA2– Low-power Sensors– Grenade Timer– Radio Performance

Sep 10, 2004 11

Sensor Suite

• Passive infrared– Long range (15m)

– Low power (10s of micro Watts)

– Wide FOV (360 degrees with 4 sensors)

– Gain: 80dB

– Wakeup

• Microphone– LPF: fc = 100Hz – 10kHz

– HPF: fc = 20Hz – 4.7kHz

– Gain: 40dB – 80dB (100-8300)

– Wakeup

• Magnetometer– High power, long startup latency

– Gain: 86dB (20,000)

Sep 10, 2004 12

Low-power Sensing through Duty-cycled Operation

• Motivation– Low-latency, high-power

sensors

– High-latency, low-power signal conditioning

• Components– Unbalanced clock

• Tsetup phase• Tsampe phase• Thold phase

– S/H switch

– S/H capacitor

– S/H unity-gain buffer

Sep 10, 2004 13

Reliability through the Grenade Timer

• Motivation• Basic idea presented by

Stajano and Anderson• Once started

– You can’t turn it off

– You can only speed it up

• Our implementation:

Sep 10, 2004 14

XSM RF Performance

Sep 10, 2004 15

Conclusions and Future Work

• Improve (or obviate) sensor wakeup circuits– Lower false-alarm rate– Low-power (zero-power?) wakeup

• Reduce sensing power (op amp FET ASIC)• Decrease signal processing power consumption

– Consider space, time, message (and energy) complexity

Sep 10, 2004 16

Discussion